Bandwidths of a physical layer (PHY) generally used for broadcasting are fixed bit rates. That is, normal digital broadcasting signals are decided to be transmitted from transmission devices to reception devices within constant delay times in accordance with buffer models. In order to realize this, encoding of a broadcasting signal formed of a video and audio is controlled so that quality (mainly image quality) of each program is optimized in a range in which a generated code amount of a program of a plurality of programs with variable length bit rates do not exceed a fixed bit rate of the physical layer.
At this time, a null packet is inserted into portions in which a code amount is insufficient for the fixed bit rate to be adjusted to the fixed bit rate.
In the physical layer, a generated code amount decreases according to a header compression technology or a variable length header technology. However, when the code amount is insufficient for the fixed bit rate, a null packet may be inserted.
Incidentally, in Advanced Television System Committee (ATSC) 3.0 or the like, a restricted bandwidth is requested to be efficiently used. Thus, since null packets which are invalid data cause a reduction in transmission efficiency, it is preferable not to use the null packets.
Ideally, the same generated code amount as a bandwidth ensured in the physical layer is considered to be allocated. Incidentally, since a generated code amount varies every moment in transmission of digital broadcasting, it is necessary to control the generated code amount with high precision in realtime. Thus, the allocation of the same generated code amount as the bandwidth ensured in the physical layer was not practical.
Accordingly, for example, in Digital Video Broadcasting Terrestrial Second Generation (DVB-T2), null packet deletion is realized to detect null packets in the physical layer and delete the null packets (see Non-Patent Literature 1). In this scheme, plural connection is realized in a seemingly widened bandwidth and a more code amount can be generated.